American Cancer Society Guidelines for the Early Detection of Cancer Pt.4

SCREENING AND SURVEILLANCE FOR THE EARLY DETECTION OF ADENOMATOUS POLYPS AND COLORECTAL CANCER :

ACS guidelines for screening and surveillance for the early detection of adenomatous polyps and colorectal cancer were updated in 2001 (Table 1), and the recommendations for stool blood testing were modified in 2003 by adding fecal immunochemical tests.2,5 There are a number of options for colorectal screening, which may be chosen based on individual risk, personal preference, and access. The ACS recommends that average-risk adults begin colorectal cancer screening at age 50 years, with one of the following options: (1) annual fecal occult blood test (FOBT) or fecal immunochemical test (FIT); (2) flexible sigmoidoscopy every 5 years; (3) annual FOBT or FIT, plus flexible sigmoidoscopy every 5 years; (4) double contrast barium enema (DCBE) every 5 years; or (5) colonoscopy every 10 years. Other tests currently are being evaluated in experimental settings, and also available to a limited degree to the public, are stool DNA testing and computed tomography exams of the colon, also referred to as virtual colonoscopy. While not recommended at this time, the ACS is carefully monitoring the accumulation of evidence related to these tests.5

The ACS recommends more intensive surveillance for individuals at higher risk for colorectal cancer. Individuals at higher risk for colorectal cancer include individuals with a history of adenomatous polyps, individuals with a personal history of curative-intent resection of colorectal cancer, individuals with a family history of either colorectal cancer or colorectal adenomas diagnosed in a first-degree relative before age 60 years, or individuals at significantly higher-risk due to a history of inflammatory bowel disease of significant duration, or individuals at significantly higher-risk due to a family history or genetic testing indicating the presence of one of two hereditary syndromes, such as hereditary nonpolyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP).2 For these individuals, increased surveillance generally means a specific recommendation for colonoscopy, if available, and may include more frequent exams and beginning exams at an earlier age.2

Recently, several research reports revealed that there is reason to be concerned about the quality of FOBT testing in the United States. In the recent comparison of stool DNA testing with FOBT, Imperiale and colleagues observed that one-time FOBT testing using the take-home method was only 13% sensitive for cancer, with poorer performance in part attributable to in-office processing of test results.12 Further, in a study of veteran males reported earlier, Collins et al examined the performance of a single sample, in-office FOBT following digital rectal examination (DRE).13 The sensitivity for advanced neoplasia of a one time FOBT when done properly is very low,14 which is why there is a strong emphasis on the importance of annual testing for patients who chose to be screened for colorectal cancer with stool blood tests. Collins and colleagues observed that when procedure is done in the office following a rectal exam, the sensitivity for advanced neoplasia was only 4.9%.13 In an accompanying article in the same journal, Nadel et al reported on a national population-based survey of primary care providers, among which one-third reported that this was the only method of stool blood testing that they used, and an additional 41% reported using both the in-office and take home methods.15 These findings provide sobering evidence that millions of FOBTs done each year literally are worthless, and according to Sox in an accompanying editorial, provide at least indirect evidence for one reason that colorectal cancer mortality hasn’t dropped more despite the volume of stool blood testing.15,16

Many physicians take the opportunity to do FOBT with stool acquired during a DRE, having little confidence that the patient will complete the preferred at-home method. However, it is clear from this evidence that in-office testing for fecal occult blood not only is wasteful of time and resources, but a negative result also provides false reassurance to the patient. While convenient, one-sample FOBT for colorectal cancer screening with stool collected during a DRE is not recommended16 and has been discouraged in previous guidelines.2
Additional data from Nadel et al reveals further problems with stool blood testing, specifically that follow up of positive FOBTs commonly is inappropriate.15 Nearly one in three physicians surveyed reported repeating the FOBT if the first test was positive, and a higher percentage reported follow up with flexible sigmoidoscopy rather than colonoscopy. One third of adults in the National Health Interview Survey (NHIS) who reported having had a positive FOBT reported that they received no follow up.15

The findings on inappropriate testing with FOBT, as well as inappropriate follow up of a positive FOBT, indicate the need for a highly focused educational campaign to help clinicians understand that FOBT testing should follow manufacturer’s instructions, and that positive tests should be followed up with colonoscopy.